.item {
    width: 300px;
    height: 350px;
    margin: 100px auto;
    border-radius: 8px;
    background: pink;
}

.item:nth-child(2n) {
    background: lightgreen;
}

.gotop-btn {
    width: 28px;
    height: 64px;
    background: url("../images/topcio.png");
    cursor: pointer;
    display: none;
    position: fixed;
    right: 70px;
    bottom: 50px;
}
.gotop-btn:hover {
    background-position: -28px 0;
}